One of the flagship models of Novaroma Industries' Formans line of reploids, Hydro Formans was designed to operate underwater, rebuilding damaged coral reefs and creating new ones. Cheerful and optimistic, he performed this work happily alongside his sister model, Aqua Formans . Recently sold to the Maverick Hunters together with several of his manufacturer's other top-selling models - a PR move to prove NI's high standards for quality and endurance - Hydro now spends his time patrolling coastlines and guarding sea-borne assets. A fish out of water only when necessary, Hydro has taken well to his new assignment and makes every attempt to share his cheer (and his jokes) with anyone working with him.

On his first mission, Hydro and Aqua responded to a raid on a scrapyard by Vile. The twins were soundly beaten with Hydro being blown apart with grenades and Aqua knocked out by vulcan fire.

Some time after being repaired, Hydro encountered Silhouette while off-duty at a beach in Able City. Stating an intention to blow up a nearby coral reef, Sil threw a grenade into the water. Failing to shoot it out of the air, Hydro dove after it. It turned out to be a trick - and a proximity grenade - and Hydro was again blown apart, losing an arm. Aqua responded to the distress call, collected her brother, and brought him back to base.

Another raid by Vile leads to Hydro and Aqua engaging him and Burnout Lily. The pair escape by air and Vile sets off explosives in the building they were fighting in. Aqua, outside helping civilians evacuate, is safe from the blast; Hydro, inside the building when the explosives went off, is not. Fortunately the explosion only burned him and he left in mostly one piece.

Pirate attacks in Maldives draw a Hunter response. Ford Benett is responsible and in the process of disabling the Avian's engine, Hydro is knocked out by Ford's crewmate Gale Chimera. Aqua is coerced on board after her twin. The pair are later released back to the Hunters after a week's captivity together.

Hydro and Aqua respond to a distress call by Layer , sent out after she responded to a distress call by Scanner Bat, who was spying on a meeting between Ford's crew (captainless as Ford was in Dopplertown at the time) and Ezui Takara. They are captured as well and their cores are given back to the Hunters in a box.

Getting their new bodies quickly thanks to being mass-produced, Hydro and Aqua put forward additional upgrade requests, their string of failed missions and lessons learned from them. The upgrade requests are granted; Hydro receives more armor and a vectored forcefield system, trading speed and versatility for power and defense. Meanwhile, Network Woman purchases and installs a robot master core into Hydro's old body. The new RM calls himself Nero.

Responding to a flash freeze and possible Maverick attack in New Times Square, Hydro and Aqua meet Mary Summers, a renegade Mega Man from Neo Arcadia. While moderately banged up from the fighting and somewhat shaken by Mary's use of ice-encased human corpses as shields and weapons, the pair force Mary into a retreat and return to base in relatively good shape.

Impulse attacks a city, Hydro and Aqua respond. While Hydro manages to free trapped civilians, Impulse escapes when the pair try to trick him into thinking they're letting him go to lower his guard. Impulse took the offer and left before they could catch him, leaving gravity to drop Hydro (who had flown to a high altitude chasing Impulse) onto Aqua and then into the ground, knocking them both out.

Contrary to the +d10, Hydro's relationship with his sister is purely platonic.

Unsurprisingly, Hydro loves swimming as well as most activities involving large amounts of water.

While superficially able to drink, anything Hydro takes in gets stored internally in one of his tanks; this is how he is able to refill his water supply in the field. It also means that one of any drink can last him an effectively indefinite period of time as he can pour the drink back out of himself and have it again.

Like all other Formans series reploids, Hydro's design is ethnically Turkish, although he carries the heritage lightly, having been constructed for an English-speaking company.

Since receiving his upgrades, Hydro has begun studying internal martial arts both for their emotional/mental benefit and because the flowing style meshes well with his forcefield system.